I will cover how to change password, name or mode (master or slave) in HC-05 Bluetooth module.
1. Arduino Uno board
2. Jumper wires
1. Upload a blank program to your Arduino.
2. Make the following connections:
TX ====> TX
RX ====> RX
VCC ====> VCC
GND ====> GND
3. Before powering up the Arduino, the little button on the HC-05 should be pressed and then released a few seconds after powering up the Arduino..
4. The HC-05 in now in AT mode and its LED will blink approximately once every 2 seconds.
5. Open serial monitor in the Arduino program. The Baud rate should be selected to 38400 and both nl and cr should be selected.
6. Check some AT commands:
Type AT and press enter
The response should be OK
AT+ROLE? and press enter
The response is 0 or 1
AT+UART? and press enter
The response is Baud rate
AT+PSWD? and press enter
The response is 1234 // that is the password.
For changing the password, command is AT+PSWD="1587"
This command will set the password to 1587
Note: you need the quotation marks around the number selected.
There are other AT commands available at this link: